1. Field of the Invention
The present invention relates to a hot compress structure and more particularly to a hot compress structure which when brought into close contact with the human body permits the heat of a heating composition to be transferred to the skin uniformly throughout the whole surface of the skin through a compress layer and which is capable of maintaining a safe temperature, not causing a low-temperature burn, for a long time and further capable of promoting local blood circulation by the generation of heat to improve local metabolism.
2. Discussion of the Prior Art
Hot compresses are used as means for treating symptoms involving local stiffness, pain and cold such as, for example, stiffness in the shoulder, muscle pain, cold hands and feet, neuralgia, rheumatism and lumbago. According to the conventional treating method of using a hot stupe, the following may be applied directly to an affected part: a towel or konnyaku jelly (a paste made from the starch of the devil's tongue), hot pack, paraffin bath, a fomentation containing a stimulative component such as cayenne-pepper extract, a disposable pocket heat, etc.
In the above-described conventional treating method of using a warmed towel or konnyaku jelly or a hot pack, there is reasonable concern that a burn could result from a high temperature or, conversely, the fomentation effect may not be obtained at a low temperature; further, a stuped condition will be obtained only for a short time because of an extremely poor retainability of a predetermined temperature at which the fomentation effect is obtained. It is further necessary to discontinue the daily activity during the treatment of this kind. Thus, various restrictions are involved in the use of conventional methods and so such treating method is deficient in simplicity.
Moveover, in the treatment using a warmed towel or konnyaku jelly, the heating source is not self-heating, so the heat will be removed by evaporation cooling from the fomentation with the lapse of time so the compress is cooled, thus having a reverse effect on the affected part.
Particularly in the case of a warmed towel or konnyaku jelly or a hot pack, it is troublesome to effect heating using boiling water or a heater, and when initially used they are so hot that it is required to use several towels or the like between them and the skin; besides, the temperature drops in a short time.
In the case of a paraffin bath, the place where it is to be used is limited and the regions to which it is to be applied are also restricted to hands and feet; further, staining of the skin is a problem, because of the use of oil.
As to a fomentation containing cayenne-pepper extract, it is said that the skin temperature is raised 1.degree. to 2.degree. C. by the stimulation of a peripheral sense of heat. And it is widely used because the method of using the same is easy. However, various problems are involved with the use of cayenne-pepper compresses such as, for example, rubefaction, eruption or skin poisoning caused by a stimulative component. Further, the skin feels a strong stimulation when the patient takes a bath after application of the compress on the skin. Thus, frequent use of such fomentation is dangerous.
In order to obtain a sufficient treating effect of a hot compress, the compress is sometimes required to have a durable heat retaining power at a certain constant temperature. For example, when a hot fomentation is used in close contact with the human body, it is sometimes required that the skin can be stuped over a long period of time at a certain constant skin temperature, more particularly, at a temperature not exceeding 44.degree. C. at which the skin does not undergo a low-temperature burn. However, such durable heat retainability is not satisfied by any of the hot fomentation means referred to above.
Further, although a disposable pocket heater is easy to use, the temperature cannot be controlled to a satisfactory extent and hence a temperature exceeding a certain level can cause a low-temperature burn, even when it is brought into pressure contact with the skin surface through a buffer material such as cloth. The temperature transfers mostly at the portion of pressure contact, thus limiting the effectiveness of the heat.
Recently, in view of the above-mentioned problems, there has been proposed a hot compress structure comprising a disposable pocket heater and a fomentation as an integral structure (Japanese Patent Publication No. 13914/78). According to this proposal, a disposable pocket heater and the cloth surface of a fomentation with ointment spread thereon are stuck together and the ointment surface is brought into contact with an affected part, whereby the heat generated from a heating composition in the pocket heater is transferred to the skin surface through the compress layer of the hot compress structure.
The hot compress structure is very easy and convenient to use because all that is required is merely taking it out of a bag and applying it directly to an affected part. However, the following problems remain to be solved.
1. In the latter compress an air permeation layer comprising an air-permeable member and a perforated film, the perforated film having air-permeable holes at a ratio of 0.055-0.001 relative to the area of the hot compress structure is utilized. Therefore, the moisture permeation is as large as 2,000 g/m.sup.2.24 hr as measured according to an ASTM method (E-96-80D method). The amount of oxygen permeated through the air permeation layer from the outside air is large and the amount of heat generated large, the resulting temperature exceeding 60.degree. C. Further, since steam is released to the exterior of the system, the internal pressure of the bag containing the heating composition does not become high and the partial pressure oxygen is held at about 1/5 atmosphere like the outside air, so the heating temperature is maintained high. PA0 2. Because of the heat generation at a high temperature, the vaporization of water is accelerated, and because of a large moisture permeation, the emanation of steam to the exterior of the system is vigorous. Consequently, the amount of water contained in the heating composition becomes small, so the oxidation of iron powder becomes insufficient and the duration of heat generation becomes short. PA0 3. The perforated film used in the working examples of the foregoing patent publication has 3.0 mm dia. holes, so that the supply of oxygen is concentrated on those holes and heat is generated only therein, with no generation of heat in the other portion free of such holes. Thus, the temperature distribution becomes non-uniform. PA0 4. Since the amount of moisture permeated through the perforated film is large, as mentioned in paragraph 1, the permeation of oxygen and steam can be done easily. Consequently, the internal pressure of the bag which contains the heating composition becomes approximately one atm.
As a result, the heating composition will move and be localized in the bag during use, thus causing variations in the temperature distribution of the hot compress structure, or causing a sense of incongruity at the applied part because the compress is applied directly to the user's skin. Such a sense of incongruity of the user can be eliminated by shaking the hot compress structure to make its temperature distribution uniform, but this is troublesome.
Because of the aforementioned drawbacks, hot compress structures proposed heretofore have not been put to practical use because of unsatisfactory retainability of a safe temperature on the skin surface to which the compress structure is applied.
Usually, a hot compress structure is applied directly to an affected part to treat neuralgia, etc. The user can perceive a change of temperature sensitively, and the temperature range required is extremely limited which is 38.degree. to 44.degree. C. Further, it is important that when applied to an affected part, the hot compress structure be capable of warming the whole of the affected part uniformly and that the heating composition in the hot compress structure should not be localized and hence not cause a sense of incongruity in use.